Methods of providing higher quality liquid kerosene based-propulsion fuels

ABSTRACT

By blending a quantity of synthetic cyclo-paraffinic kerosene fuel blending component comprising at least 99.5 mass % of carbon and hydrogen content and at least 50 mass % of cyclo-paraffin into kerosene base fuel, kerosene based-propulsion fuels can be upgraded to higher quality kerosene based-propulsion fuels such as jet fuel or rocket fuel to meet certain specification and/or increase volumetric energy content of the propulsion fuel.

The present application claims the benefit of pending U.S. ProvisionalApplication Ser. No. 62/270,192, filed 21 Dec. 2015, the entiredisclosure of which is hereby incorporated by reference.

FIELD OF THE INVENTION

This invention relates to methods of providing higher qualitykerosene-based propulsion fuels. More specifically, the inventionrelates to methods of upgrading kerosene-based propulsion fuels to fuelshaving enhanced properties using synthetic fuel blending components.

BACKGROUND OF THE INVENTION

Typical jet fuels and liquid kerosene rocket fuels are prepared in arefinery from a crude mineral oil source. Typically the crude mineraloil is separated by means of distillation into a distillate kerosenefraction boiling in the aviation fuel range or a more purified liquidkerosene rocket fuel. If required, these fractions are subjected tohydroprocessing to reduce sulfur, oxygen, and nitrogen levels.

Increasing demand for jet fuel and the environmental impact of aviationrelated emissions places the aviation industry at the forefront oftoday's global energy challenge. The increased demand forpetroleum-based fuels has resulted in a higher production of greenhousegases. In particular, the aviation industry accounts for about 2% ofglobal CO₂ emissions. The aviation transport sector is growing 3-5% yearon year, and due to the projected increasing demand for fuel andincreasing production of CO₂ emissions, there is a need to exploremethods to increase environmentally-friendly fuel sources while meetingjet fuel specifications.

Perhaps more tangible than the global impact of greenhouse gases is theimpact of local emissions from aircraft. Emissions near and aroundairports have a direct impact on the air composition and therefore havebeen linked with poor local air quality, which can be further linked toimpacts on human health. Sooty particulates and oxides of sulfur andnitrogen are considered to be contributors to poor local air quality.Thus, local air quality is seen as an integral element in the pursuit ofenvironment-friendly fuels.

Petroleum-derived jet fuels inherently contain both paraffinic andaromatic hydrocarbons. In general, paraffinic hydrocarbons offer themost desirable combustion cleanliness characteristics for jet fuels.Aromatics generally have the least desirable combustion characteristicsfor aircraft turbine fuel. In aircraft turbines, certain aromatics, suchas naphthalenes, tend to burn with a smokier flames and release agreater proportion of their chemical energy as undesirable thermalradiation than other more saturated hydrocarbons.

The closest current option for reducing aviation emissions is blendingsynthesized paraffinic kerosene (“SPK”) from Fischer-Tropsch orhydrogenated vegetable oil with conventional jet fuel. Up to 50% byvolume of SPK is permitted by the alternative jet fuel specificationASTM D7566. If the resulting blend meets the specification, it can becertified and considered equivalent to conventional, petroleum-derivedjet fuel. Typically, these synthesized paraffinic kerosenes contain amixture of normal and branched paraffin according to ASTM D7566.

It is important that novel fuels meet their respective jet fuelspecifications without having a detrimental impact on safety or aircraftperformance. Because SPK is purely paraffinic and absent of botharomatics and sulfur, it does not exhibit all of the desired propertiesexpected from a jet fuel. For example, a gas to liquidsFischer-Tropsch-derived fuel is not considered an on-spec fuel in itspure state due to its lower density. Further, SPK fuels tend to have lowvolumetric energy density, which may require more fuel than can beaccommodated in aircraft fuel tanks for long distance flights.

Kerosene fuels can also be used as liquid rocket fuels. MIL-DTL-25576defines two grades of kerosene fuels, rocket propellant (RP) fuels knownas RP-1 and RP-2, for use in rocket engines. These fuels, while stillkerosene-type fuels, have some different property requirements from jetfuels. RP fuels have a higher minimum flash point at 60° C., a lowermaximum freezing point at −51° C., higher temperature thermal stabilityrequirement at 355° C., lower maximum total aromatics content of 5%volume, and reduced density range of 799-815 kg/m³ at 15° C., andreduced distillation range, with T10 between 185° C. and 210° C. andmaximum distillation end point of 274° C.

SUMMARY OF THE INVENTION

In accordance with certain of its aspects, in one embodiment of theinvention, provided is a method of increasing volumetric energy contentof a kerosene based-propulsion fuel comprising:

a. providing a quantity of kerosene base fuel having a boiling point inthe range of 130° C. to 300° C., at atmospheric pressure, flash point of38° C. or above measured by ASTM D56, and a density at 15° C. of atleast 760 kg/m³;

b. providing a quantity of synthetic cyclo-paraffinic kerosene fuelblending component comprising at least 99.5 mass % of carbon andhydrogen content and at least 50 mass % of cyclo-paraffin, saidcyclo-paraffinic kerosene fuel blending component having a boiling pointof at most 300° C., at atmospheric pressure, flash point of 38° C. orabove, a density at 15° C. of at least 800 kg/m³, and freezing point of−60° C. or lower; and

c. blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component and the kerosene base fuel in amount effective toincrease the volumetric energy content providing a blended fuel.

In certain of its aspects, in one embodiment of the invention, the smokepoint of the blended fuel is increased compared with the kerosene basefuel.

The features and advantages of the invention will be apparent to thoseskilled in the art. While numerous changes may be made by those skilledin the art, such changes are within the spirit of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The drawings illustrate certain aspects of some of the embodiments ofthe invention, and should not be used to limit or define the invention.

FIG. 1 shows the volumetric energy density (MJ/m³) of the jet fuelblends based on paraffinic kerosene content (vol. %) in Jet A of variousfuels from Examples described herein.

FIG. 2 shows a plot of the aromatics content (vol. %) versus volumetricenergy density (MJ/m³) of the various jet fuel blends from Examplesdescribed herein.

FIG. 3 shows the smoke point increase of jet fuel with volumetric energydensity (MJ/m³) of the various jet fuel blends from Examples describedherein.

FIG. 4 shows the freezing point (° C.) of various jet fuel blends fromExamples described herein versus volumetric energy density (MJ/m³).

DETAILED DESCRIPTION OF THE INVENTION

In an embodiment of the invention, it has been found that by blending aquantity of certain synthetic cyclo-paraffinic kerosene fuel blendingcomponents comprising at least 99.5 mass % of carbon and hydrogencontent and at least 50 mass % of cyclo-paraffin into a kerosene basefuel, the fuel can be upgraded to meet certain specifications and/orincrease its volumetric energy content for jet and rocket fuelapplications.

In one embodiment, it has been found that the volumetric energy contentof a fuel can be increased without increase in its aromatic content by:

a. providing a quantity of kerosene base fuel having a boiling point inthe range of 130° C. to 300° C., at atmospheric pressure, flash point of38° C. or above measured by ASTM D56, and a density at 15° C. of atleast 760 kg/m³, preferably at least 770 kg/m³;

b. providing a quantity of a synthetic cyclo-paraffinic kerosene fuelblending component comprising at least 99.5 mass % of carbon andhydrogen content and at least 50 mass % of cyclo-paraffin, saidcyclo-paraffinic kerosene fuel blending component having a boiling pointof at most 300° C., at atmospheric pressure, flash point of 38° C. orabove, a density at 15° C. of at least 800 kg/m³, and freezing point of−60° C. or lower; and

c. blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component to the kerosene base fuel in amount effective toincrease the volumetric energy content preferably using D338, preferablyat least 0.1% increase in the volumetric energy content.

Volumetric energy content can be calculated as energy per unit volumeusing the following equation:

Energy per unit volume (MJ/m³)=(energy per unit mass (MJ/kg))*(density(kg/m³))

Energy per unit mass can be obtained by one of several methods,including ASTM D4529, D3338, D4809, or IP12 by way of example. Theincrease in volumetric energy content is relative so any of thesemethods can be used as long as the same method is used.

As used herein, “lower” in context of freezing points (e.g., the term“X° C. or lower”) means that the temperature is equal to or lower thanthe X temperature. For example, for a freezing point of “−60° C. orlower”, the temperature may be, for example, −60° C., −61° C., −65° C.,−70° C., etc., as long as the temperature is not higher than −60° C.

In certain embodiments, the kerosene-based fuel component may originatefrom petroleum or be synthetically derived from biomass or othernon-biomass resources. Aromatics content in a jet fuel can be determinedby ASTM D1319. Aromatics content for synthetic blend components can bedetermined by ASTM D2425. The aromatic content of the blended jet fuelis typically determined by ASTM D1319. Equivalent total aromatic contentbetween two fuels means the total aromatic content measured by thesemethods give an aromatic content within +/−1.5 vol. %. Minimal increaseof aromatic content is generally less than 3 vol. %, preferably lessthan 2 vol. %, more preferably less than 1.5 vol. %, or more preferablywithout an increase that is within the precision of measurement foraromatic content, or even a decrease in aromatic content.

The method above may also produce a fuel having an improved smoke pointas compared with the kerosene base fuel component without thecyclo-paraffinic kerosene fuel blending component. In an embodiment, thesmoke point is at least 1 mm greater than the kerosene base fuel asmeasured by ASTM D1322.

ASTM International (“ASTM”) and the United Kingdom Ministry of Defense(“MOD”) have taken the lead roles in setting and maintainingspecification for civilian aviation turbine fuel and jet fuel. Therespective specifications issued by these two organizations are verysimilar, but not identical. Many other countries issue their ownnational specifications for jet fuel, but are very nearly or completelyidentical to either the ASTM or MOD specification. ASTM D1655 is theStandard Specification for Aviation Turbine Fuels and includesspecifications for Jet A and Jet A-1. Defense Standard 91-91 is the MODspecification for Jet A-1 and is the dominant fuel specification for JetA-1 outside of the United States.

Jet A-1 is the most common jet fuel and is produced to aninternationally standardized set of specifications. In the UnitedStates, Jet A is the primary grade of jet fuel. Another jet fuel that isused in civilian aviation is called Jet B. Jet B is a wide-cut, lighterfuel in the naphtha-kerosene region that is used for its enhancedcold-weather performance Jet A and Jet A-1 are specified in ASTM D1655.Jet B is specified in ASTM D6615.

Alternatively, jet fuels are classified by militaries around the worldwith a different system of NATO or JP (Jet Propulsion) numbers. Some arealmost identical to their civilian counterparts and differ only by theamounts of a few additives. For example, Jet A-1 is similar to JP-8.Both Jet A-1 and JP-8 specifications require a freezing point of −47° C.or lower. Jet A specification requires a freezing point of −40° C. orlower as does the military equivalent F-24. Jet B is similar to JP-4that requires a freezing point of −58° C. or lower. Other jet fuelspecifications for militaries may include JP-5 that requires a freezingpoint of −46° C. or lower and JP-7 that requires a freezing point of−43.3° C. or lower and the RP grades that requires a freezing point of−51° C. or lower.

Further, some jet fuel specification have more stringent requirement forflight in more challenging environments. For cold climates, such as theAntarctic, AN-8 is a jet fuel specification with a freezing point of−58° C. or lower. AN-8 fuel is used for turbine engines and other powerapplications that require low freeze point for low temperatureapplications and storage.

Typically, jet fuel is a product boiling for more than 90 vol. % at from130° C. to 300° C. (ASTM D86), having a density in the range from 775 to840 kg/m³, preferably from 780 to 830 kg/m³, at 15° C. (e.g. ASTMD4052), an initial boiling point in the range 130° C. to 190° C. and afinal boiling point in the range 220° C. to 300° C., at atmosphericpressure, a flash point of 38° C. or above (ASTM D56), a kinematicviscosity at −20° C. (ASTM D445) suitably from 1.2 to 8.0 mm²/s and afreeze point of −40° C. or below for Jet A specification, preferably−47° C. or below for Jet A-1 and JP-8 specifications, and preferably−58° C. or below for AN-8 specification.

Jet fuel will typically meet one or more of the following civilstandards. Jet A-1 requirements are in ASTM D1655 or DEF STAN 91-91(British Ministry of Defense Standard DEF STAN 91-91/Issue 7 amendment 3of 2 Feb. 2015 (or later issues) for Turbine Fuel, Aviation “KeroseneType,” Jet A-1, NATO code F-35, Joint Service Designation AVTUR, orversions current at the time of testing), as well as some airporthandling requirements of the IATA Guidance Material for Aviation TurbineFuels Specifications. Jet A requirements are in ASTM D1655. Military jetfuel requirements are similar to civil requirements but usually morestringent for select properties and in the use of additives; theserequirements are published by respective governments. For example, thesecan include MIL-DTL-83133 which defines JP-8 as used by US federalagencies.

Due to the differences in the specifications and depending on locationsand intended use, it is desirable to upgrade the fuel to achieve thespecification that the fuel must meet in order to fly in certainregions. For example, it may be desirable to upgrade a jet fuel whichmeets the Jet A specification to a fuel that has a lower freezing pointconsistent with the Jet A-1 specification requirement, particularlywithout an increase in its aromatic content. In another example, it maybe desirable to upgrade a jet fuel to a cold climate specification, suchas AN-8 jet fuel specification, which requires an even lower freezingpoint.

It has been found that by blending a quantity of syntheticcyclo-paraffinic kerosene fuel blending component comprising at least99.5 mass % of carbon and hydrogen content and at least 50 mass % ofcyclo-paraffin, the cyclo-paraffinic kerosene fuel blending componenthaving a boiling point of at most 300° C. at atmospheric pressure, flashpoint of 38° C. or above, and a density at 15° C. of at least 800 kg/m³,and freezing point of −60° C. or below, one can upgrade a kerosene basefuel to meet certain specifications.

As used herein, upgrading to meet a fuel specification means blending afuel that does not meet the specification standard to meeting thestandard for such fuel specification. For jet fuels, it is particularlydesirable to upgrade the jet fuel without increasing its aromaticcontent. To meet a jet fuel specification property means that the jetfuel meets the requirements of at least one of the above mentionedspecifications, as determined by standard test methods, such as fromASTM, IP, or other such industry-recognized standards bodies. Testmethods for determining if a fuel meets a specification may include:

TABLE 1 Test for Jet Fuel Specification Properties Test ASTM MethodAcidity (mgKOH/g) D3242 Density at 15° C. (g/cm³) D4052 Hydrogen Content(mass %) D7171 Flash Point (° C.) D56 Freeze Point (° C.) D5972Viscosity (mm²/s) D445 Total Sulfur (mass %) D4294 Mercaptan sulfur(mass %) D3227 Smoke Point (mm) D1322 Naphthalenes (vol. %) D1840Aromatics (vol. %) D1319 Net Heat of Combustion (MJ/kg) D3338 InitialBoiling Point (IBP) (° C.) D86 Final Boiling Point (FBP) (° C.) D86

MIL-DTL-25576E specifies 2 grades of rocket fuel, RP-1 and RP-2, whichare identical except for the maximum sulfur content. RP-1 has a maximumallowable sulfur content of 0.0030 mass %, while RP-2 has a maximumallowable sulfur content of 0.00001 mass %. Both RP-1 and RP-2 have amaximum aromatics content of 5 vol. %, a 10% distillation point between185° C. and 210° C., a distillation end point maximum of 274° C., aminimum flash point of 60° C., a density range at 15° C. of 799-815kg/m³, a maximum freezing point of −51° C., a minimum hydrogen contentof 13.8 mass %, and a thermal stability test temperature of 355° C.

Kerosene Base Fuel or Kerosene Range Hydrocarbon Component

A kerosene base fuel or kerosene range hydrocarbon component is anykerosene that may be useful as a jet or rocket fuel, or a jet or rocketfuel blending component (other than the synthetic cyclo-paraffinickerosene fuel blending component described herein) having a boilingpoint in the range of 130° C. to 300° C., at atmospheric pressure (asmeasured by ASTM D86), preferably in the range of 140° C. to 300° C.,and most preferably in the range of 145° C. to 300° C. For a jet fuelblending component, the kerosene base fuel (whether single stream or amixture) can have a flash point of 38° C. or above (measured by ASTMD56), and a density at 15° C. of at least 760 kg/m³ (as measured byD4052). For liquid rocket fuel, the kerosene range hydrocarbon componentcan have a boiling point in the range of 145° C. to 300° C., preferablyin the range of 145° C. to 270° C.; a flash point of 60° C. or above,measured by ASTM D56; and a density at 15° C. of at most 815 kg/m³. Thekerosene base fuel or kerosene range hydrocarbon component may originatefrom petroleum or be synthetically derived from biomass, or othernon-biomass resources. In certain embodiments, the kerosene base fuelmay be any petroleum-derived jet fuel known to skilled artisans,including kerosene fuels meeting at least one of Jet A, Jet A-1, F-24,JP-8, Jet B or AN-8 specification. Preferably the kerosene base fuel isa kerosene that can meet the jet fuel specification properties accordingto the invention.

For example, petroleum-derived kerosene fuels meeting Jet A or Jet A-1requirements and a kerosene stream used in Jet A or Jet A-1 productionare listed in Table 2. It is also contemplated that petroleum-derivedkerosene fuels which do not meet Jet A or Jet A-1 specifications may beused as kerosene base fuels that can be upgraded to meet suchspecifications according to the present invention.

TABLE 2 Jet Fuel Produced Using: Straight run kerosene stream. Causticwashing of straight run kerosene. A sweetening process such as Merox ®,Merichem ®, or Bender process. Hydroprocessed jet fuel.

As another example, the low boiling fraction as separated from a mineralgas oil may be used as such or in combination with petroleum-derivedkerosene, suitably made at the same production location. As the lowboiling fraction may already comply with a jet fuel specification, it isevident that the blending ratio between said component and thepetroleum-derived kerosene may be freely chosen. The petroleum-derivedkerosene will typically boil for more than 90 vol. % within the usualkerosene range of 145° C. to 300° C. (ASTM D86), depending on grade anduse. It will typically have an initial boiling point in the range 130°C. to 190° C., and a final boiling point in the range 220° C. to 300° C.It will typically have a density from 775 to 840 kg/m³ at 15° C. (e.g.,ASTM D4052 or IP 365). Its kinematic viscosity at −20° C. (ASTM D445)might suitably be from 1.2 to 8.0 mm²/s.

The kerosene base fuel or kerosene range hydrocarbon component may be astraight run kerosene fraction as isolated by distillation from a crudeoil source or a kerosene fraction isolated from the effluent of typicalrefinery conversion processes, preferably hydrocracking. The kerosenefraction may also be the blend of straight run kerosene and kerosene asobtained in a hydrocracking process. Suitably the properties of themineral derived kerosene are those of the desired jet fuel as definedabove.

Aromatic content of the kerosene base fuel may vary in the range of 0 to25 vol. %, preferably 3 to 25 vol. %, more preferably 15 to 20 vol. %based on the fuel (as measured by ASTM 1319). Typical density of thepetroleum-derived kerosene at 15° C. is in the range of 775 kg/m³ to 840kg/m³ (as measured by D4052). The kerosene base fuel most useful for theinventive process may have a density of at least 760 kg/m³, morepreferably at least 775 kg/m³, to preferably at most 840 kg/m³, and morepreferably at most 820 kg/m³. The aromatic content of the kerosene rangehydrocarbon component for liquid rocket fuel may vary in the range of 0to 10 vol. %, preferably 0 to 5 vol. %.

The kerosene base fuel may be a single stream from a refining stream(petroleum-derived kerosene), or a mixture of one or more refiningstreams, or a mixture of refining streams and one or more synthetickerosene components, or one or more synthetic kerosene streams (otherthan the synthetic cyclo-paraffinic blending component) approved by ASTMD7566 or equivalent specifications.

For Example, kerosene range hydrocarbon component may be aliphaticmineral spirits having flash points in the range of 60° C. up to 120°C., preferably 63° C. up to 120° C. Preferably, the aliphatic mineralspirits also have density at 15° C. from 790 to 820 kg/m³. Thesealiphatic mineral spirits are typically mixtures of normal-, iso- andcyclo-paraffins. Aliphatic mineral spirits are fractionated fromselected feedstock. Their low aromatics content is obtained by deephydrogenation. Commercially available kerosene range hydrocarboncomponent may include ShellSol™ D (de-aromatised) grades available fromShell Chemical Co. such as for example, ShellSol D60, D70, D80, D90 andD100 or suitably fractionated aliphatic mineral spirits having flashpoints in the appropriate range. Other aliphatic mineral spirits such asIsopar™ isoparaffinic fluids or NORPAR™ fluids may be used. Kerosenerange hydrocarbon component may also be kerosene base fuel so long as itcan meet the kerosene range hydrocarbon component properties and thefinal blend can meet the rocket fuel specifications.

Synthetic Cyclo-Paraffinic Kerosene Fuel Blending Component

The synthetic cyclo-paraffinic kerosene fuel blending component isgenerally characterized as a liquid composed of individual hydrocarbonsuseable as a jet fuel blending component and having at least thefollowing properties: comprising at least 99.5 mass % of carbon andhydrogen content and at least 50 mass % of cyclo-paraffin.

For jet fuel applications, the cyclo-paraffinic kerosene fuel blendingcomponent can typically have a boiling point of at most 300° C., atatmospheric pressure; flash point of 38° C., or above; a density at 15°C. of at least 800 kg/m³, preferably at least 810 kg/m³, preferably atmost 845 kg/m³, more preferably at most 830 kg/m³, most preferably inthe range of 810 to 818 kg/m³; and a freezing point of −60° C. or below,preferably of −65° C. or below, more preferably of −70° C. or below.

For rocket fuel applications, preferably the synthetic cyclo-paraffinickerosene fuel blending component is generally characterized as a liquidcomposed of individual hydrocarbons useable as a rocket fuel blendingcomponent and having at least the following properties: comprising atleast 99.5 mass % of carbon and hydrogen content and at least 50 mass %of cyclo-paraffin. The cyclo-paraffinic kerosene fuel blending componentcan typically have a flash point of at least 38° C., preferably at least45° C., preferably at least 50° C., more preferably at least 55° C.,more preferably at least 60° C.; a density at 15° C. of at least 799kg/m³; and a freezing point of −60° C. or lower, preferably of −65° C.or lower, more preferably of −70° C. or lower. Further, thecyclo-paraffinic kerosene fuel blending component can have good thermalstability for use in rocket fuel. The cyclo-paraffinic kerosene fuelblending component typically has a final boiling point below 300° C.,more preferably below 290° C., more preferably below 280° C., mostpreferably below 274° C.

The synthetic cyclo-paraffinic kerosene fuel blending componentpreferably has a maximum iso-paraffin and n-paraffin content of lessthan 50 mass %, preferably less than 40 mass %, less than 35 mass %, orless than 30 mass % (ASTM D2425 or optionally can be measured by GCxGC).The synthetic cyclo-paraffinic kerosene fuel blending componentpreferably has at least 60 mass %, at least 65 mass %, or at least 70mass % of cyclo-paraffinic content (ASTM D2425 or optionally can bemeasured by GCxGC). The aromatic content of the syntheticcyclo-paraffinic kerosene fuel blending component is preferably at most1.5 mass %, at most 1 mass %, or at most 0.5 mass % (ASTM D2425 oroptionally can be measured by GCxGC).

In certain embodiments, the synthetic cyclo-paraffinic kerosene fuelblending component is derived from biomass (bio-derived cyclo-paraffinickerosene fuel blending component). As used herein, the term “biomass”refers to, without limitation, organic materials produced by plants(such as leaves, roots, seeds and stalks), and microbial and animalmetabolic wastes. Common biomass sources include: (1) agriculturalresidues, including corn stover, straw, seed hulls, sugarcane leavings,bagasse, nutshells, cotton gin trash, and manure from cattle, poultry,and hogs; (2) wood materials, including wood or bark, sawdust, timberslash, and mill scrap; (3) municipal solid waste, including recycledpaper, waste paper and yard clippings; and (4) energy crops, includingpoplars, willows, switch grass, miscanthus, sorghum, alfalfa, prairiebluestream, corn, soybean, and the like. The term also refers to theprimary building blocks of the above, namely, lignin, cellulose,hemicellulose and carbohydrates, such as saccharides, sugars andstarches, among others.

Common biomass-derived feedstocks include lignin and lignocellulosicderivatives, cellulose and cellulosic derivatives, hemicellulose andhemicellulosic derivatives, carbohydrates, starches, monosaccharides,disaccharides, polysaccharides, sugars, sugar alcohols, alditols,polyols, and mixtures thereof. Preferably, the biomass-derived feedstockis derived from material of recent biological origin such that the ageof the compounds, or fractions containing the compounds, is less than100 years old, preferably less than 40 years old, and more preferablyless than 20 years old, as calculated from the carbon 14 concentrationof the feedstock.

The biomass-derived feedstocks may be derived from biomass using anyknown method. Solvent-based applications are well known in the art.Organosolv processes use organic solvents such as ionic liquids,acetone, ethanol, 4-methyl-2-pentanone, and solvent mixtures, tofractionate lignocellulosic biomass into cellulose, hemicellulose, andlignin streams (Paszner 1984; Muurinen 2000; and Bozell 1998).Strong-acid processes use concentrated hydrochloric acid, phosphoricacid, sulfuric acid or other strong organic acids as thedepolymerization agent, while weak acid processes involve the use ofdilute strong acids, acetic acid, oxalic acid, hydrofluoric acid, orother weak acids as the solvent. Enzymatic processes have also recentlygained prominence and include the use of enzymes as a biocatalyst todeconstruct the structure of the biomass and allow further hydrolysis touseable feedstocks. Other methods include fermentation technologiesusing microorganisms, Fischer-Tropsch reactions and pyrolysistechnologies, among others.

In one embodiment, the synthetic cyclo-paraffinic kerosene fuel blendingcomponent is derived from the conversion of a biomass-derived feedstockcontaining one or more carbohydrates, such as starch, monosaccharides,disaccharides, polysaccharides, sugars, and sugar alcohols, orderivatives from lignin, hemicellulose and cellulose using abioreforming processes. As used herein, the term “bioreforming” refersto, without limitation, processes for catalytically convertingbiomass-derived oxygenated hydrocarbons to lower molecular weighthydrocarbons and oxygenated compounds using aqueous phase reforming,hydrogenation, hydrogenolysis, hydrodeoxygenation and/or otherconversion processes involving the use of heterogeneous catalysts.Examples of various bioreforming processes include those technologiesdescribed in U.S. Pat. Nos. 8,053,615, 8,017,818; and 7,977,517 (all toCortright and Blommel, and entitled “Synthesis of Liquid Fuels andChemicals from Oxygenated Hydrocarbons”); U.S. Pat. No. 8,642,813 (toQiao et al., and entitled “Reductive Biomass Liquefaction”); U.S. PatentApplication Publication No. 2012/0198760 (to Blommel et al., andentitled Methods and Systems for Making Distillate Fuels from Biomass);and U.S. Patent Application Publication No. 2013/0263498 (to Kania etal., and entitled Production of Distillate Fuels from Biomass-DerivedPolyoxygenates); and U.S. Patent Application Pub. No. 2013/0036660 (toWoods et al. and entitled “Production of Chemicals and Fuels fromBiomass”), all of which are incorporated herein by reference.

Alternatively, the synthetic cyclo-paraffinic kerosene fuel blendingcomponent may be produced using natural gas or syngas-derived feedstocksused in a bioreforming process. For example, certain alkanols and othermixed oxygenated hydrocarbons derived from natural gas or syngas usingFischer-Tropsch type reactions may have application in the abovedescribed bioreforming processes, and can be used as a feedstock toprovide the synthetic cyclo-paraffinic kerosene fuel blending componentof the present invention.

In its application, a bioreforming process is used to convert oxygenatedhydrocarbons to an intermediate stream of mixed oxygenates, with theresulting mixed oxygenates subsequently converted to C₈₊ compoundscontaining the desired synthetic cyclo-paraffinic kerosene fuel blendingcomponent. Examples of various oxygenated hydrocarbons include any oneor more sugars, such as glucose, fructose, sucrose, maltose, lactose,mannose or xylose, or sugar alcohols, such as arabitol, erythritol,glycerol, isomalt, lactitol, malitol, mannitol, sorbitol, xylitol,arabitol, glycol, and other oxygenated hydrocarbons. Additionalnon-limiting examples of oxygenated hydrocarbons include variousalcohols, ketones, aldehydes, furans, hydroxy carboxylic acids,carboxylic acids, diols and triols.

The oxygenated hydrocarbons are reacted in an aqueous solution withhydrogen over a deoxygenation catalyst to produce a stream of mixedoxygenates. The oxygenates will generally include, without limitation,oxygenated hydrocarbons having 1 to 4 oxygen atoms (e.g., mono-, di-,tri- and tetra-oxygenated hydrocarbons). The mono-oxygenatedhydrocarbons typically include alcohols, ketones, aldehydes, cyclicethers, furans, and pyrans, while the di-oxygenated hydrocarbonstypically include diols, hydroxy ketones, lactones, furfuryl alcohols,pyranyl alcohols, and carboxylic acids.

The deoxygenation catalyst is a heterogeneous catalyst having one ormore active materials capable of catalyzing a reaction between hydrogenand the oxygenated hydrocarbons to remove one or more of the oxygenatoms from the oxygenated hydrocarbon to produce the oxygenatesdescribed above. The active materials may include, without limitation,Cu, Re, Fe, Ru, Ir, Co, Rh, Pt, Pd, Ni, W, Os, Mo, Ag, Au, alloys andcombinations thereof, adhered to a support. The deoxygenation catalystmay include these elements alone or in combination with one or more Mn,Cr, Mo, W, V, Nb, Ta, Ti, Zr, Y, La, Sc, Zn, Cd, Ag, Au, Sn, Ge, P, Al,Ga, In, Tl, Ce and combinations thereof. The support may be any one of anumber of supports, including a support having carbon, silica, alumina,zirconia, titania, tungsten, vanadia, chromia, zeolites,heteropolyacids, kieselguhr, hydroxyapatite, and mixtures thereof. Thedeoxygenation catalyst may also include an acidic support modified orconstructed to provide a desired functionality. Heteropolyacids are aclass of solid-phase acids exemplified by such species asH_(3+x)PMo_(12-x) V_(x)O₄₀, H₄SiW₁₂O₄₀, H₃PW₁₂O₄₀, and H₆P2W₁₈O₆₂, andhave a well-defined local structure, the most common of which is thetungsten-based Keggin structure.

To produce oxygenates, a stream of oxygenated hydrocarbons is combinedwith water to provide an aqueous feedstock solution. The feedstocksolution is then reacted with hydrogen in the presence of thedeoxygenation catalyst at deoxygenation temperature and pressureconditions, and weight hourly space velocity, effective to produce thedesired oxygenates. In condensed phase liquid reactions, the pressurewithin the reactor must be sufficient to maintain the reactants in thecondensed liquid phase at the reactor inlet. For liquid phase reactions,the reaction temperature may be from about 80° C. to 300° C., and thereaction pressure from about 72 psig to 1300 psig. For vapor phasereactions, the reaction should be carried out at a temperature where thevapor pressure of the oxygenated hydrocarbon is at least about 0.1 atm(and preferably a good deal higher), and the thermodynamics of thereaction are favorable. This temperature will vary depending upon thespecific oxygenated hydrocarbon compound used, but is generally in therange of from about 100° C. to 600° C. for vapor phase reactions.

The synthetic cyclo-paraffinic kerosene fuel blending component issubsequently produced using an acid condensation catalyst and a reactantstream that includes the mixed oxygenate stream above as a firstreactant and a second reactant having an average oxygen to carbon ratioof 0.2 or less, in the presence of water. The first reactant (i.e., themixed oxygenates produced above) can be generally described as havingthe formula C_(x)H_(y)O_(z), with x representing 2 to 12 carbon atomsand z representing 1 to 12 oxygen atoms, and an average oxygen to carbonratio of between 0.2 and 1.0. Collectively, the average oxygen to carbonratio of the first reactant should be about 0.2 to 1.0, calculated asthe total number of oxygen atoms (z) in the oxygenates of the firstreactant divided by the total number of carbon atoms (x) in theoxygenates of the first reactant. Alternatively, the first reactant mayhave an average oxygen content per molecule of about 1 to 4, calculatedas the total number of oxygen atoms (z) in the oxygenates of the firstreactant divided by the total number of molecules of oxygenates in thefirst reactant. The total number of carbon atoms per molecule, oxygenatoms per molecule and total molecules in the first reactant may bemeasured using any number of commonly known methods, including (1)speciation by gas chromatography (GC), high performance liquidchromatography (HPLC), and other methods known to the art and (2)determination of total oxygen, carbon, and water content by elementalanalysis. Oxygen present in water, carbon dioxide, or carbon monoxide isexcluded from the determination of reactant oxygen to carbon ratio.

The second reactant includes one or more hydrocarbons and/or oxygenatedhydrocarbons having a general formula C_(p)H_(r)O_(s), with prepresenting 2 to 7 carbon atoms and s representing 0 to 1 oxygen atoms.When the second reactant is derived from a recycle stream as describedbelow, the second reactant may also contain residual oxygenatedhydrocarbons containing 2 oxygen atoms. Collectively, the average oxygento carbon ratio of the second reactant should be less than 0.2,calculated as the total number of oxygen atoms (s) in the oxygenatedhydrocarbons of the second reactant divided by the total number ofcarbon atoms (p) in the hydrocarbons and oxygenated hydrocarbons of thesecond reactant. Alternatively, the second reactant may have an averageoxygen per molecule ratio of less than 1.5, calculated as the totalnumber of oxygen atoms (s) in the oxygenated hydrocarbons of the secondreactant divided by the total number of molecules of hydrocarbons andoxygenated hydrocarbons in the second reactant. The second reactant mayalso be characterized as having an average normal boiling point of lessthan 210° C., or less than 200° C., or less than 190° C.

The second reactant will generally include C⁷⁻ alkanes, C⁷⁻ alkenes, C⁷⁻cycloalkanes, C⁷⁻ cycloalkenes, C⁷⁻ alcohols, C⁷⁻ ketones, C⁷⁻ aryls,and mixtures thereof. Examples of the second reactant compounds include,without limitation, C⁷⁻ alkanes and C⁷⁻ alkenes having from 4 to 7carbon atoms (C₄₋₇ alkanes and C₄₋₇ alkenes), such as butane,iso-butane, butene, isobutene, pentane, pentene, 2-methylbutane, hexane,hexene, 2-methylpentane, 3-methylpentane, 2,2-dimethylbutane,2,3-dimethylbutane, cyclohexane, heptane, heptene, methyl-cyclohexaneand isomers thereof. The C⁷⁻ aryls will generally consist of an aromatichydrocarbon having 6 or 7 carbon atoms, whether in either anunsubstituted (phenyl), mono-substituted or multi-substituted form. TheC⁷⁻ cycloalkanes and C⁷⁻ cycloalkenes have 5, 6 or 7 carbon atoms andmay be unsubstituted, mono-substituted or multi-substituted. In the caseof mono-substituted and multi-substituted compounds, the substitutedgroup may include straight chain C₁₋₂ alkyls, straight chain C₂alkylenes, straight chain C₂ alkynes, or combinations thereof. Examplesof desirable C⁷⁻ cycloalkanes and C⁷⁻ cycloalkenes include, withoutlimitation, cyclopentane, cyclopentene, cyclohexane, cyclohexene,methyl-cyclopentane, methyl-cyclopentene, ethyl-cyclopentane,ethyl-cyclopentene, and isomers thereof.

The second reactant may be provide from any source, but is preferablyderived from biomass or a biomass-derived feedstock. For example,although a biomass-derived feedstock is preferred, it is contemplatedthat all or a portion of the second reactant may originate from fossilfuel based compounds, such as natural gas or petroleum. All or a portionof the second reactant may also originate from any one or morefermentation technologies, gasification technologies, Fischer-Tropschreactions, or pyrolysis technologies, among others. Preferably, at leasta portion of the second reactant is derived from the product stream andrecycled to be combined with the first reactant to provide at least aportion of the reactant stream.

When a portion of the second reactant is derived from the product streamfollowing the condensation reaction, the product stream is separatedinto a first portion containing C₈₊ compounds and a second portioncontaining C⁷⁻ compounds to be recycled and used as a portion of thesecond reactant. Alternatively, the product stream may be firstseparated to a water fraction and an organic fraction, with the organicfraction then separated into a first portion containing the desired C₈₊compounds and a second portion containing the C⁷⁻ compounds to berecycled and used as a portion of the second reactant. Processes forseparating liquid mixtures into their component parts or fractions arecommonly known in the art, and often involve the use of a separatorunit, such as one or more distillation columns, phase separators,extractors, purifiers, among others.

The condensation reaction is performed using catalytic materials thatexhibit acidic activity. These materials may be augmented through theaddition of a metal to allow activation of molecular hydrogen forhydrogenation/dehydrogenation reactions. The acid condensation catalystmay be either an acidic support or an acidic heterogeneous catalystcomprising a support and an active metal, such as Pd, Pt, Cu, Co, Ru,Cr, Ni, Ag, alloys thereof, or combinations thereof. The acidcondensation catalyst may include, without limitation, aluminosilicates,tungstated aluminosilicates, silica-alumina phosphates (SAPOs), aluminumphosphates (ALPO), amorphous silica alumina (ASA), acidic alumina,phosphated alumina, tungstated alumina, zirconia, tungstated zirconia,tungstated silica, tungstated titania, tungstated phosphates, acidmodified resins, heteropolyacids, tungstated heteropolyacids, silica,alumina, zirconia, titania, tungsten, niobia, zeolites, mixturesthereof, and combinations thereof. The acid condensation catalyst mayinclude the above alone or in combination with a modifier or metal, suchas Re, Cu, Fe, Ru, Ir, Co, Rh, Pt, Pd, Ni, W, Os, Mo, Ag, Au, alloysthereof, and combinations thereof.

Examples of applicable acidic condensation catalysts includebifunctional pentasil zeolites, such as ZSM-5, ZSM-8 or ZSM-11. Thezeolite with ZSM-5 type structure is a particularly preferred catalyst.Other suitable zeolite catalysts include ZSM-12, ZSM-22, ZSM-23, ZSM-35and ZSM-48. Zeolite ZSM-5, and the conventional preparation thereof, isdescribed in U.S. Pat. Nos. 3,702,886; Re. 29,948 (highly siliceousZSM-5); U.S. Pat. Nos. 4,100,262 and 4,139,600, all incorporated hereinby reference. Zeolite ZSM-11, and the conventional preparation thereof,is described in U.S. Pat. No. 3,709,979, which is also incorporatedherein by reference. Zeolite ZSM-12, and the conventional preparationthereof, is described in U.S. Pat. No. 3,832,449, incorporated herein byreference. Zeolite ZSM-23, and the conventional preparation thereof, isdescribed in U.S. Pat. No. 4,076,842, incorporated herein by reference.Zeolite ZSM-35, and the conventional preparation thereof, is describedin U.S. Pat. No. 4,016,245, incorporated herein by reference. Anotherpreparation of ZSM-35 is described in U.S. Pat. No. 4,107,195, thedisclosure of which is incorporated herein by reference. ZSM-48, and theconventional preparation thereof, is taught by U.S. Pat. No. 4,375,573,incorporated herein by reference. Other examples of zeolite catalystsare described in U.S. Pat. No. 5,019,663 and U.S. Pat. No. 7,022,888,also incorporated herein by reference.

The specific C₈₊ compounds produced will depend on various factors,including, without limitation, the make-up of the reactant stream, thetype of oxygenates in the first reactant, the hydrocarbons andoxygenated hydrocarbons in the second reactant, the concentration of thewater, condensation temperature, condensation pressure, the reactivityof the catalyst, and the flow rate of the reactant stream as it affectsthe space velocity (the mass/volume of reactant per unit of catalyst perunit of time), gas hourly space velocity (GHSV), and weight hourly spacevelocity (WHSV). The condensation temperature and pressure conditionsmay be selected to more favorably produce the desired products in thevapor-phase or in a mixed phase having both a liquid and vapor phase. Ingeneral, the condensation reaction should be conducted at a temperatureand pressure where the thermodynamics of the reactions are favorable. Ingeneral, the condensation temperature should be between 100° C. and 400°C. and the reaction pressure between 72 psig and 2000 psig.

The above condensation reactions result in the production of C₈₊alkanes, C₈₊ alkenes, C₈₊ cycloalkanes, C₈₊ cycloalkenes, C₈₊ aryls,fused aryls, C₈₊ alcohols, C₈₊ ketones, oxygenated C₈₊ aryls, oxygenatedfused aryls, and mixtures thereof. The C₈₊ alkanes and C₈₊ alkenes have8 or more carbon atoms, and may be branched or straight chained alkanesor alkenes. The C₈₊ alkanes and C₈₊ alkenes may also include fractionscontaining C₈, C₉, C₁₀, C₁₁, C₁₂, C₁₃, C₁₄ compounds (C₈₋₁₄ fraction),or C₁₂, C₁₃, C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, C₁₉, C₂₀, C₂₁, C₂₂, C₂₃, C₂₄compounds (C₁₂₋₂₄ fraction), or more than 25 carbon atoms (C₂₅₊fraction), with the C₈₋₁₄ fraction directed to the syntheticcyclo-paraffinic kerosene fuel blending component, the C₁₂₋₂₄ fractiondirected to diesel fuel, and the C₂₅₊ fraction directed to heavy oilsand other industrial applications. Examples of various C₈₊ alkanes andC₈₊ alkenes include, without limitation, octane, octene,2,2,4,-trimethylpentane, 2,3-dimethyl hexane, 2,3,4-trimethylpentane,2,3-dimethylpentane, nonane, nonene, decane, decene, undecane, undecene,dodecane, dodecene, tridecane, tridecene, tetradecane, tetradecene,pentadecane, pentadecene, hexadecane, hexadecane, heptyldecane,heptyldecene, octyldecane, octyldecene, nonyldecane, nonyldecene,eicosane, eicosene, uneicosane, uneicosene, doeicosane, doeicosene,trieicosane, trieicosene, tetraeicosane, tetraeicosene, and isomersthereof.

The C₈₊ cycloalkanes and C₈₊ cycloalkenes have 8 or more carbon atomsand may be unsubstituted, mono-substituted or multi-substituted. In thecase of mono-substituted and multi-substituted compounds, thesubstituted group may include a branched C₃₊ alkyl, a straight chain C₁₊alkyl, a branched C₃₊ alkylene, a straight chain C₂₊ alkylene, astraight chain C₂₊ alkyne, a phenyl or a combination thereof. In oneembodiment, at least one of the substituted groups include a branchedC₃₊ alkyl, a straight chain C₁₊ alkyl, a branched C₃₊ alkylene, astraight chain C₂₊ alkylene, a straight chain C₂₊ alkyne, a phenyl or acombination thereof. Examples of desirable C₈₊ cycloalkanes and C₈₊cycloalkenes include, without limitation, ethyl-cyclopentane,ethyl-cyclopentene, ethyl-cyclohexane, ethyl-cyclohexene, and isomersthereof.

The C₈₊ product compounds may also contain high levels of alkenes,alcohols and/or ketones, which may be undesirable in certain fuelapplications or which lead to coking or deposits in combustion engines,or other undesirable combustion products. In such event, the C₈₊compounds may undergo a finishing step. The finishing step willgenerally involve a hydrotreating reaction that removes a portion of theremaining carbon-carbon double bonds, carbonyl, hydroxyl, acid, ester,and ether groups.

The moderate fractions above (C₈-C₁₈) may be separated for use as thesynthetic cyclo-paraffinic kerosene fuel blending component, while theC₁₂-C₂₄ fraction may be separated for diesel fuel, and the heavierfraction (C₂₅₊) separated for use as a heavy oil or cracked to produceadditional gasoline and/or diesel fractions. A C₁₂-C₁₈ fraction can alsobe separated for rocket fuel applications. Separation processes are wellknown in the art and generally involve one or more distillation columnsdesigned to facilitate the separation of desired compounds from aproduct stream. The distillation will be generally operated at atemperature, pressure, reflux ratio, and with an appropriate equipmentdesign, to recover the portion of the C₈₊ compounds which conform to theboiling point characteristics of the synthetic cyclo-paraffinic kerosenefuel blending component as described above.

Additional Propulsion Fuel Blending Component

The additional propulsion fuel blending component may be any fuelblending component which can be considered a kerosene base fuel asdescribed above. The additional propulsion fuel blending component mayalso be naphtha generally used for blending to manufacture Jet B fuel.

Other Components

Optionally, the fuel composition may further comprise a fuel additiveknown to a person of ordinary skill in the art. In certain embodiments,the fuel additive can be used from about 0.00005% by weight to about0.20% by volume, based on the total weight or volume of the fuelcomposition. The fuel additive can be any fuel additive approved for usein jet fuel or rocket fuel known to those of skill in the art. Infurther embodiments, the fuel additive may be antioxidants, thermalstability improvers, lubricity improvers, fuel system icing inhibitors,metal deactivators, static dissipaters, other aviation-approvedadditives and combinations thereof.

The amount of a fuel additive in the fuel composition disclosed hereinmay be from about 0.00005% by weight to less than about 0.20% by volume,based on the total amount of the fuel composition. In some embodiments,the amount is in wt. % based on the total weight of the fuelcomposition. In other embodiments, the amount is in vol. % based on thetotal volume of the fuel composition. In yet other embodiments, theamount is in mass per volume of the fuel composition. The amount willnormally be within limits mandated or recommended within the appropriatefuel specification.

Illustrative examples of fuel additives are described in greater detailbelow. Lubricity improvers are one example. They were first used inaviation fuels as corrosion inhibitors to protect ferrous metals in fuelhandling systems, such as pipelines and fuel storage tanks, fromcorrosion. It was discovered that they also provided additionallubricity performance, reducing the wear in components of the aircraftengine fuel system, such as gear pumps and splines, where thin fuellayers separate moving metal components. Nowadays, these additives areonly used for lubricity improvement. The lubricity improver may bepresent in the fuel composition at a concentration up to about 23 mg/L,based on the total volume of the fuel composition, and in accordancewith jet fuel specification limits.

Antioxidants can also be used herein. Antioxidants prevent the formationof gum depositions on fuel system components caused by oxidation offuels in storage and/or inhibit the formation of peroxide compounds incertain fuel compositions. The antioxidant may be present in the fuelcomposition at a concentration up to 24 mg/L, based on the total volumeof the fuel composition.

Static dissipaters reduce the effects of static electricity generated bymovement of fuel through high flow-rate fuel transfer systems. Thestatic dissipater may be present in the fuel composition at aconcentration up to about 5 mg/L, based on the total volume of the fuelcomposition.

Fuel system icing inhibitors (also referred to as anti-icing additives)reduce the freezing point of water precipitated from jet fuels due tocooling at high altitudes and prevent the formation of ice crystalswhich could restrict the flow of fuel to the engine. Certain fuel systemicing inhibitors can also act as a biocide. The fuel system icinginhibitor may be present intentionally in the fuel composition at aconcentration from about 0.02 to about 0.2 volume %, based on the totalvolume of the fuel composition.

Metal deactivators suppress the catalytic effect that some metals,particularly copper, have on fuel oxidation. The metal deactivator maybe present in the fuel composition at a concentration up to about 5.7mg/L active matter, based on the total volume of the fuel composition.

Thermal stability improvers are used to inhibit deposit formation in thehigh temperature areas of the aircraft fuel system. The thermalstability improver may be present in the fuel composition at aconcentration up to about 256 mg/L, based on the total volume of thefuel composition.

Blending and Using

In certain embodiments, volumetric energy content of a jet fuel can beincreased with minimal increase of the aromatic content of the fuel. Bythe term minimal increase of aromatic content, typically the increase inaromatic content is less than 2 vol. %, preferably less than 1.5 vol. %,or preferably without an increase that is within the precision ofmeasurement for aromatic content, or preferably even decreasing, basedon the jet fuel. Higher volumetric energy content is usually associatedwith higher aromatics. Thus, it is unexpected to increase the volumetricenergy content of a fuel without an increase in its aromatic content.

A quantity of kerosene base fuel as described above (which is differentor other than cyclo-paraffinic kerosene fuel blending component) may beblended with a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component in an amount effective or sufficient to increase thevolumetric energy content of the final blended fuel compared to thekerosene base fuel, preferably at least 0.1% increase in the volumetricenergy content as calculated from the Net Heat of Combustion estimatedby ASTM D3338 and multiplied by density.

In some embodiments, the smoke point of the blended fuel may alsoincrease compared with the kerosene base fuel.

Optionally, the blended fuel may be blended with an additionalpropulsion fuel blending component to produce the kerosene-basedpropulsion fuel.

The propulsion fuel may be blended at refineries or terminals, intankers, or at the location of application, as well as at any otherlocation that may have blending capabilities. Various methods andequipment required for such blending activities are commonly known inthe art, and may be applied as needed depending on the particularpropulsion fuel desired.

The amount of the synthetic cyclo-paraffinic kerosene fuel blendingcomponent may suitably be in an amount of 1 to 97 vol. %, preferably 3to 97 vol. %, preferably 5 to 97 vol. %, more preferably 10 to 97 vol.%, more preferably 15 to 97 vol. % provided that the amount issufficient to increase volumetric energy content at least 0.1%. Theamount may vary depending on the kerosene base fuel and/or the desiredspecification to upgrade to and/or amount of desired volumetric energycontent increase desired. The amount of the synthetic cyclo-paraffinickerosene fuel blending component of the blend is preferably at least 1vol. %, preferably at least 3 vol. %, more preferably at least 5 vol. %,more preferably at least 10 vol. %, more preferably at least 15 vol. %,based on the blended fuel. The amount of the synthetic cyclo-paraffinickerosene fuel blending component will vary depending on the kerosenebase fuel used.

The kerosene base fuel may be upgraded to meet Jet A-1 specification orJP-8 specification (e.g., when the kerosene base fuel has a freezingpoint of above −47° C.) by blending the synthetic cyclo-paraffinickerosene fuel blending component in an amount effective or sufficient tolower the freezing point of the blended fuel to −47° C. or lower. Forexample, Jet A or F-24 jet fuel may be upgraded to meet Jet A-1 or JP-8specification in such manner.

In some embodiments, the kerosene base fuel may be upgraded to meet AN-8specification (e.g., when the kerosene base fuel has a freezing point ofabove −58° C.) by blending the synthetic cyclo-paraffinic kerosene fuelblending component in an amount effective or sufficient to lower thefreezing point of the blended fuel to −58° C. or lower. For example, anyone of Jet A, F-24, Jet A-1, JP-8, or JP-5 jet fuel may be upgraded tomeet Jet AN-8 specification.

In some embodiments, the kerosene base fuel is upgraded to meet Jet Aspecification (e.g., when the kerosene base fuel have a freezing pointof above −40° C.) by blending the synthetic cyclo-paraffinic kerosenefuel in an amount effective or sufficient to lower the freezing point ofthe blended fuel to −40° C. or lower. For example, refinery streams,synthetic fuel streams and mixtures thereof that have a freezing pointof above −40° C. and/or have a density of at least 760 kg/m³ may beupgraded to meet Jet A specification.

In certain embodiments, a kerosene fuel can be upgraded to meet Jet A-1specification or JP-8 specification by;

a. providing a quantity of kerosene base fuel having a boiling point inthe range of 130° C. to 300° C., at atmospheric pressure, flash point of38° C. or above measured by above measured by ASTM D56, a density at 15°C. of at least 775 kg/m³ and freezing point of above −47° C.;

b. providing a quantity of synthetic cyclo-paraffinic kerosene fuelblending component described above; and

c. blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component to the kerosene base fuel in amount sufficient tolower the freezing point of the blended fuel to −47° C. or lower.

In certain embodiments, a kerosene fuel can be upgraded to meet AN-8specification by;

a. providing a quantity of kerosene base fuel having a boiling point inthe range of 130° C. to 300° C., at atmospheric pressure, flash point of38° C. or above measured by ASTM D56, and a density at 15° C. of atleast 775 kg/m³ and freezing point of above −58° C.;

b. providing a quantity of synthetic cyclo-paraffinic kerosene fuelblending component described above; and

c. blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component to the kerosene base fuel in amount sufficient tolower the freezing point of the blended fuel to −58° C. or lower.

In certain embodiments, a kerosene fuel can be upgraded to meet Jet Aspecification by;

a. providing a quantity of kerosene base fuel having a boiling point inthe range of 130° C. to 300° C., at atmospheric pressure, flash point of38° C. or above measured by ASTM D56, a density at 15° C. of at least760 kg/m³ and freezing point of above −40° C.;

b. providing a quantity of synthetic cyclo-paraffinic kerosene fuelblending component described above; and

c. blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component to the kerosene base fuel in amount sufficient tolower the freezing point of the blended fuel to −40° C. or lower.

In some embodiments, the blended jet fuel may preferably have a densityof equal or above 800 kg/m³. The blended jet fuel may preferably have anaromatic content of less than or equal to 25 vol. %, more preferablyless than or equal to 20 vol. %.

In some embodiments, the inventive method may be used to meet any of thestandard specifications for Aviation Turbine fuels described above.

The increase in volumetric energy content and/or smoke point increasecan be seen by operating a jet engine comprising burning the jet fuelproduced by the method described above in such jet engine.

In another aspect, a fuel system is provided comprising a fuel tankcontaining the fuel composition produced by the methods described above.Optionally, the fuel system may further comprise an engine coolingsystem having a recirculating engine coolant, a fuel line connecting thefuel tank with the internal combustion engine, and/or a fuel filterarranged on the fuel line. Some non-limiting examples of internalcombustion engines include reciprocating engines (e.g., diesel engines),jet engines, some rocket engines, and gas turbine engines.

In some embodiments, the fuel tank is arranged with a cooling system soas to allow heat transfer from the recirculating engine coolant to thefuel composition contained in the fuel tank. In other embodiments, thefuel system further comprises a second fuel tank containing a secondfuel for a jet engine and a second fuel line connecting the second fueltank with the engine. Optionally, the first and second fuel lines can beprovided with electromagnetically operated valves that can be opened orclosed independently of each other or simultaneously.

In another aspect, an engine arrangement is provided comprising aninternal combustion engine, a fuel tank containing the fuel compositiondisclosed herein, a fuel line connecting the fuel tank with the internalcombustion engine. Optionally, the engine arrangement may furthercomprise a fuel filter and/or an engine cooling system comprising arecirculating engine coolant. In some embodiments, the internalcombustion engine is a jet engine.

The smoke point increase can be seen by burning the jet fuel produced bythe methods described above by providing the jet fuel to the fuel systemand/or jet engine and operating such fuel system and/or jet engine.

Rocket fuel can be used in a rocket engine system that includes acombustion chamber, an oxidizer supply, a fuel delivery circuitconnected to a fuel supply, a faceplate having a plurality of openingstherethrough, and an injector assembly positioned at the combustionchamber. Such a system is described, for example, in U.S. Pat. No.7,685,807 and U.S. Pat. No. 7,827,781.

A liquid rocket fuel useful to meet RP-1 or RP-2 grade rocket fuels maybe produced by blending a quantity of the synthetic cyclo-paraffinickerosene fuel blending component and a quantity of the kerosene rangehydrocarbon component in amount sufficient to meet a flash point of atleast 60° C. and a final boiling point of 274° C. or lower. The blendedrocket fuel preferably have a freezing point of −51° C. or below, aflash point of at least 60° C., a density in the range of 799-815 kg/m³at 15° C., and a volumetric energy density in the range of 34,380-35,070MJ/m³. The blended rocket fuel can also have a hydrogen content of atleast 13.8 mass %. In one embodiment, the net heat of combustion of theblended rocket fuel is at least 43.03 MJ/kg. The blended rocket fuel canalso have a sulfur content of no more than 0.0030 mass %. The sulfurrequirement for RP-1 is 0.0030 mass % or below and RP-2 0.00001 mass %or below by ASTM D-5623. The liquid rocket fuel may also be blended tomeet a thermal stability requirement at a temperature of at least 355°C. The preferable amount of synthetic cyclo-paraffinic kerosene fuelblending component in the final liquid rocket fuel is at least 1 vol. %,preferably at least 3 vol. %, preferably at least 5 vol. %, preferablyat least 10 vol. %, preferably at least 15 vol. %, preferably at least20 vol. %, preferably at least 25 vol. %, or more preferably at least 30vol. %, based on the final rocket fuel blend. The preferable amount ofsynthetic cyclo-paraffinic kerosene fuel blending component in the finalliquid rocket fuel is at most 97 vol. %, preferably at most 95 vol. %,preferably at most 90 vol. %, preferably at most 85 vol. %, preferablyat most 80 vol. %, or more preferably at most 75 vol. %, based on thefinal rocket fuel blend.

By blending a quantity of the synthetic cyclo-paraffinic kerosene fuelblending component and a quantity of the kerosene range hydrocarboncomponent, it was found that a higher quality liquid fuel suitable foruse as liquid rocket fuel may be produced. The blended liquid rocketfuel may be considered to be a biofuel containing rocket fuel.

As used herein, a “low” or “lower” in the context of propulsion fuelproperties embraces any degree of decrease or reduction compared to anaverage commercial petroleum jet fuel property containing equivalenttotal aromatics content under the same or equivalent conditions.

As used herein, a “high” or “higher” in the context of propulsion fuelproperties embraces any degree of increase compared to an averagecommercial petroleum jet fuel property containing equivalent totalaromatics content under the same or equivalent conditions.

As used herein, an “increase” in the context of propulsion propertiesembraces any degree of increase compared to a previously measured jetfuel property under the same or equivalent conditions. Thus, theincrease is suitably compared to the jet fuel property of the fuelcomposition prior to incorporation of the synthetic cyclo-paraffinickerosene fuel blending component. Alternatively, the property increasemay be measured in comparison to an otherwise analogous jet fuelcomposition (or batch or the same fuel composition); for example, whichis intended (e.g., marketed) for use in a jet turbine engine, withoutadding the bio-based cyclo-paraffinic kerosene fuel blending componentto it.

As used herein, a “decrease” or “reduction” in the context of propulsionfuel properties embraces any degree of decrease or reduction compared toa previously measured jet fuel property under the same or equivalentconditions. Thus, the decrease or reduction is suitably compared to theproperty of the jet fuel composition prior to incorporation of thesynthetic cyclo-paraffinic kerosene fuel blending component.Alternatively, the property decrease may be measured in comparison to anotherwise analogous jet fuel composition (or batch or the same fuelcomposition); for example, which is intended (e.g., marketed) for use ina jet turbine engine, without adding the synthetic cyclo-paraffinickerosene fuel blending component to it.

In the context of the present invention, “use” of a syntheticcyclo-paraffinic kerosene fuel blending component in a propulsion fuelcomposition means incorporating the component into the jet fuel,typically as a blend (i.e., a physical mixture) with one or more jetfuel components and optionally with one or more jet fuel additives.

Accordingly, in one embodiment of the invention, there is provided theuse of a synthetic cyclo-paraffinic kerosene fuel blending componentdescribed above to increase the volumetric energy content of a jet fuel.Accordingly, in another embodiment of the invention, there is providedthe use of a synthetic cyclo-paraffinic kerosene fuel blending componentdescribed above to upgrade a kerosene base fuel to meet a Jet A-1specification. Accordingly, in another embodiment of the invention,there is provided the use of a synthetic cyclo-paraffinic kerosene fuelblending component described above to upgrade a kerosene base fuel tomeet a Jet A specification. Accordingly, in another embodiment of theinvention, there is provided the use of a synthetic cyclo-paraffinickerosene fuel blending component described above to upgrade a kerosenebase fuel to meet a Jet AN-8 specification.

Suitably, the synthetic cyclo-paraffinic kerosene fuel blendingcomponent described above is used in an amount to increase the smokepoint, preferably to increase the smoke point at least 1 mm greater thanthe kerosene base fuel (e.g., petroleum based jet fuel) as measured byASTM D1322 (automated method). When using a jet fuel compositionprepared by the method disclosed herein, a jet airplane equipped with ajet turbine engine, a fuel tank containing the jet fuel compositionprepared according to methods disclosed herein, and a fuel lineconnecting the fuel tank with the jet turbine engine. Thus, a jet enginemay be operated by burning in such jet engine a jet fuel describedherein.

Accordingly, in another embodiment of the invention, there is providedthe use of a synthetic cyclo-paraffinic kerosene fuel blending componentcomprising at least 99.5 mass % of carbon and hydrogen content and atleast 50 mass % of cyclo-paraffin, said cyclo-paraffinic kerosene fuelblending component having a boiling point of at most 300° C., atatmospheric pressure, flash point of at least 38° C., a density at 15°C. of at least 799 kg/m³, and a freezing point of −60° C. or lower, toproduce a liquid rocket fuel.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof are shown by way ofexamples herein described in detail. It should be understood, that thedetailed description is not intended to limit the invention to theparticular form disclosed, but on the contrary, the intention is tocover all modifications, equivalents and alternatives falling within thespirit and scope of the present invention as defined by the appendedclaims. The person skilled in the art will readily understand that,while the invention is illustrated making reference to one or more aspecific combinations of features and measures, many of those featuresand measures are functionally independent from other features andmeasures such that they can be equally or similarly appliedindependently in other embodiments or combinations.

The present invention will be illustrated by the following illustrativeembodiment, which is provided for illustration only and is not to beconstrued as limiting the claimed invention in any way.

ILLUSTRATIVE EXAMPLES Test Methods Jet Fuel Specification Tests andMethods

A jet fuel can be verified to meet a given specification by testing thefuel's properties specified by the governing specification.

Energy Per Unit Volume or Energy Per Unit Mass

The energy per unit weight (or gravimetric energy density) of a fuel issimply its Net Heat of Combustion as determined by ASTM D3338. Theenergy per unit volume (or volumetric energy density) can be calculatedby multiplying the fuel's Net Heat of Combustion (determined by ASTMD3338) by the fuel's density (determined by ASTM D4052).

Materials Comparative Examples

A petroleum-derived jet fuel sourced from Convent Terminal in Convent,La. is provided as a comparative example of Jet A or a kerosene basefuel component. A synthetic jet fuel component sourced from Shell MiddleDistillate Synthesis plant in Bintulu, Malaysia having (99.9 wt. %paraffin content with iso-paraffin and n-paraffin content of 98.7 wt. %)is provided as a comparative example of GTL1. Another synthetic jet fuelcomponent sourced from Pearl GTL plant in Qatar having (100.0 wt. %paraffin content with iso-paraffin and n-paraffin content of 96.3 wt. %)is provided as a comparative example of GTL2. A jet fuel component fromhydroprocessed esters and fatty acid sourced from UOP having (98.1 mass% paraffins, 1.9 mass % cyclo-paraffins) is provided as a comparativeexample of HEFA. The specification properties for each comparativeexample are summarized in Table 3 below.

TABLE 3 Specification Properties of Fuel Components ASTM Test Method JetA GTL1 GTL2 HEFA Acidity (mgKOH/g) D3242 0.003 0.001 0.001 0.003 Densityat 15° C. (-kg/m³) D4052 798.4 735.9 753.8 756.7 Hydrogen Content (mass%) D5291 14.005 15.595 15.42 14.73 Flash Point (° C.) D56 45 43 56.5 43Freeze Point (° C.) D5972 −43.2 −54.6 −49.3 −57.3 Viscosity (mm²/s) at−20° C. D445 4.037 2.450 4.146 4.795 Total Sulfur (ppm) D5453 NA <1* 1<1* Total Sulfur (mass %) D4294 0.151 NA NA NA Mercaptan sulfur (mass %)D3227 6 NA NA NA Smoke Point D1322 24.3 >50.0* >50.0* >50.0* (mm)(automated) Naphthalenes (vol. %) D1840 1.26 NA 0.0 NA Aromatics (vol.%) D1319 17.5 NA NA NA D6379 NA 0.1 <0.1* 0.1 Net Heat of CombustionD3338 43.318 44.246 44.136 44.145 (MJ/kg) Distillation Temperature atD86 176.2 161.0 184.4 162.9 10% Boiling Point (° C.) Final Boiling Point(° C.) D86 274.4 195.9 234.3 277.8 *Actual values were beyond theindicated detection limit

Example 1—Production of Synthetic Cyclo-Paraffinic Kerosene from CornStarch

A three step catalytic process as described above utilizing aqueousphase reforming (APR), dehydration/oligomerization (DHOG) andhydrotreating (HT), was used to convert corn syrup tocyclo-paraffin-rich organic product. Two distinct beds of APR catalystdeveloped by Virent, Inc. (Madison, Wis.) were used. The first APRcatalyst included palladium, molybdenum, and tin metals on a tungstenmodified zirconia support, while the second APR catalyst includedpalladium and silver metals on a tungsten modified zirconia support. TheDHOG catalyst included palladium and silver metals on a tungstenmodified zirconia support, also provided by Virent, Inc. The HT catalystwas prepared by CRI with a nickel metal loading on an alumina support.

The catalysts were loaded into separate fixed-bed, tubular reactorsconfigured in series such that the liquid product from one step was fedto the next step. A 60% 43DE corn syrup in water mixture by weight wasfed across the system with the process conditions shown in Table 4.

TABLE 4 Start of Run Conditions for APR, DHOG, and HT APR I APR II DHOGHT WHSV wt_(feed)/(wt_(catalyst) hr) 0.8 0.8 0.8 1.6 Added Hydrogenmol_(H2)/mol_(feed) 1.4 0.8 — 0.5 Average Reactor ° C. 210 250 280 370Temperature Pressure Psig 1800 900 900 1300

A two-pass hydrotreating configuration was used. The hydrotreatingprocess included an intermediate distillation step in between each passto remove the components heavier than the 300° C. end point for jetfuel. The liquid from the HDO-DHOG-HT train was fractionatedcontinuously within the same plant. The SK fraction was collected,combined all together, and re-fed across the HT catalyst andfractionation portion of the plant at the same conditions shown in Table4 for the HT step.

The resulting product composition of the liquid organic product is shownin Table 5, which includes a comparison of the composition and carbonnumber of the product pre-fractionation, after the first HT pass, andafter the second HT pass.

For alternative applications, the fractionation can be tuned to producea diesel fraction that is primarily C₁₂-C₂₄, or a rocket fuelapplication that is primarily C₁₂-C₁₈ (rocket fuel cut).

TABLE 5 Liquid Organic Product Composition by GC × GC—Full Range and SKFraction SK Fraction SK Fraction Full Range Post- Post- Pre-fractionation fractionation Specification fractionation 1 Pass HT 2 PassHT Cyclo-paraffins wt. % 37.3 52.2 82.2 Paraffins wt. % 14.3 14.6 16.9Aromatics wt. % 6.5 27.8 0.5 PNA wt. % 0.5 2.1 0.0 Unclassified* wt. %41.4 3.4 0.6 Total wt. % 100.0 100.0 100.0 Carbon Number C7− wt. % 33.21.7 0.8 C8-C18 wt. % 52.4 95.6 98.5 C19+ wt. % 13.6 2.4 0.4 Unclassifiedwt. % 0.8 0.4 0.3 Total wt. % 100.0 100.0 100.0 *Method set up to lookfor compounds between C7-C18 in jet fuel range, so C7− and C19+compounds are not classified into a class. In case of “Full Range”material, majority of “Unclassified” compounds were paraffins.The process was run to produce greater than 420 liters (110 gallons) ofsynthetic cyclo-paraffinic kerosene for product testing. The product wasstored in two 55 gallon drums and one 16 gallon drum. 20 milligrams perliter of butylated hydroxyltoluene (BHT) antioxidant additive was addedto each drum as is standard fuel handling practice for jet fuel.Examples 3 were tested fuel from this example.

Example 2—Production of Synthetic Cyclo-Paraffinic Kerosene fromLignocellulose

A woody biomass material was deconstructed by a 3rd party to produce ahydrolysate. This hydrolysate was ion exchanged to remove inorganicimpurities and diluted so the carbon containing fraction was 50% byweight, with the balance being water.

A three step catalytic process as described in Example 1 utilizingaqueous phase reforming (APR), dehydration/oligomerization (DHOG) andhydrotreating (HT) was used to convert the hydrolysate tocyclo-paraffinic rich organic product under the process conditions shownin Table 6.

TABLE 6 Process Conditions for APR and DHOG APR I DHOG WHSVwt_(feed)/(wt_(catalyst) hr) 0.7 0.7 Added Hydrogen mol_(H2)/mol_(feed)6.4 1.1 Average Reactor Temperature ° C. 210 270 Pressure psig 1050 600

An organic phase product from the APR-DHOG continuous system wascollected throughout the run, combined all together, and fed to aseparate plant to perform the hydrotreating (HT) step. The HT steputilized a two-pass hydrotreating configuration as described in Example1, which included an intermediate distillation step between each pass toremove the components heavier than the 300° C. end point for jet fuel.The HT catalyst was prepared by CRI with a nickel metal loading on analumina support and loaded into a fixed-bed, tubular reactor. A 1:1co-loading of amorphous silica alumina was used to distribute thecatalyst.

TABLE 7 Process Conditions for HT I and II HT I HT II WHSVwt_(feed)/(wt_(catalyst) hr) 3 1.7 Added Hydrogen mol_(H2)/mol_(feed)13.8 13.6 Average Reactor ° C. 290 290 Temperature Pressure psig 800 800The product composition of the final SK liquid organic product is shownin Table 8. The 3^(rd) column from Table 5 in Example 1 is included toshow the similarity of the product from both feedstock sources. Sincethe compositions of the products are very similar, it follows that thephysical properties are very similar as well, as shown in Table 9.

TABLE 8 Liquid Organic Product Composition by ASTM D2425 Example 1Example 2 Specification Corn Syrup Woody Biomass Cyclo-paraffins wt. %83 74 Paraffins wt. % 17 25 Aromatics wt. % <0.3* <0.3* Olefins wt. %<0.3* <0.3* PNA wt. % <0.3* <0.3* Other wt. % <0.3* <0.3* Total wt. %100 100 *Actual values were beyond the indicated detection limit

TABLE 9 Physical Properties of SK Produced from Corn Syrup andBiomass-Derived Feedstocks Example Feedstock ASTM D1655 Example ExampleJet A/A-1 SK 1 SK 2 Test Spec Corn Woody Specification Test MethodRequirement Syrup Biomass Aromatics, vol. % D1319 ≤25 0.0 0.2 Heat ofCombustion D4809 ≥42.8 43.3 43.3 (measured), MJ/kg Distillation:D86/D7345** IBP, ° C. 149 146 10% recovered, ≤205 178 172 ° C. 50%recovered, 217 227 ° C. 90% recovered, 266 280 ° C. EP, ° C. ≤300 292300 Residue, % vol. ≤1.5 1.2 2** Loss, % vol. ≤1.5 0.7 0 Flash point, °C. D56 ≥38 44 45 Freezing Point, ° C. D5972 ≤−47 <−78* <−60* Density @15° C., D4052 775-840 818 813 kg/m³ Thermal Stability D3241 >260 ≥355≥325*** Breakpoint, ° C. Net Heat of D3338 ≥42.8 43.3 43.3 combustion(MJ/kg) *Actual values were beyond the indicated detection limit **D7345micro-distillation performed due to sample size, high residue likely anartifact of test method. No HDO-SK sample analyzed by D86 had a highresidue. ***Sample not tested higher than 325° C. due to sample size,breakpoint at some temperature higher.

Example 3—Comparative Jet Fuel Blends

Several series of Example and Comparative Example jet fuel blends wereprepared using Comparative Example Jet A, Example SK1 from Example 1,Comparative Example HEFA, Comparative Example GTL1, and ComparativeExample GTL2. These jet fuel blends and their indicated blend ratios aresummarized in Table 10.

TABLE 10 Jet A content SK1 content (Vol. %) (Vol. %) Example Series 3-164.5 35.5 3-2 43.0 57.0 3-3 32.3 67.7 3-4 26.9 73.1 3-5 21.5 78.5 3-610.8 89.2 Jet A content HEFA content (Vol. %) (Vol. %) Comparative A-164.5 35.5 Example Series A-2 43.0 57.0 Jet A content GTL1 content (Vol.%) (Vol. %) Comparative B-1 64.5 35.5 Example Series B-2 43.0 57.0 B-332.3 67.7 B-4 16.1 83.9 B-5 10.8 89.2 B-6 5.4 94.6 Jet A content GTL2content (Vol. %) (Vol. %) Comparative C-1 64.5 35.5 Example Series C-243.0 57.0 C-3 32.3 67.7 C-4 16.1 83.9 C-5 10.8 89.2 C-6 5.4 94.6

The Jet fuel Blends above were tested for jet fuel specificationproperties. The results are provided in Tables 11 below.

Aromatic contents of the blends were calculated by linear blending; thatis, multiplying the percentage of Kerosene base fuel (Jet A) in thecomparative example blend by the aromatic content of the Kerosene basefuel (as determined by D1319).

Gravimetric and volumetric energy densities of the two-component blendswere calculated by linear blending. That is, for components α and β withrespective volumetric contents [α] and 1−[α], respective gravimetricenergy densities γ_(α) and γ_(β), and respective densities of ρ_(α) andρ_(β), the gravimetric and volumetric energy densities of resultingblends can be calculated as follows:

Gravimetric energy density of blend of α and β=[α]*γ_(α) +(1−[α])*γ_(β)Volumetric energy density of blend of α andβ=[α]*γ_(α)*ρ_(α)+(1−[α])*γ_(β)*ρ_(β)

TABLE 11-1 Key Specification Properties of Example Series 3 SK1 contentin SK1/Jet A blend (vol. %) 0.0 35.5 57.0 67.7 73.1 78.5 89.2 100.0Comparative Examples ASTM Jet A 3-1 3-2 3-3 3-4 3-5 3-6 SK1 Test MethodProperty Aromatic D1319 or 18.6 12.0 8.0 6.0 5.0 4.0 2.0 0 Content (vol.%) calculated Density at 15° C. D4052 0.7984 0.8037 0.8071 0.8087 0.80960.8104 0.8121 0.8138 (g/cm³ Freezing Point D5972 −43.2 −48.8 NA −58.0−61.1 −64.9 <−77.0* <−76.0* (° C.) Smoke Point D1322 24.3 26.1 27.9 28.329.3 29.9 30.2 31.3 (mm) (automated) Hydrogen D5291 14.01 14.15 14.2114.26 14.21 14.25 14.27 14.4 Content (mass %) Net Heat of D3338 or 43.343.3 43.3 43.3 43.3 43.3 43.3 43.4 Combustion or calculated GravimetricEnergy Density (MJ/kg) Volumetric Calculated 34,600 34,900 35,000 35,10035,100 35,100 35,200 35,300 Energy Density (MJ/m³) *Actual values werebeyond the indicated detection limit

TABLE 11-2 Key Specification Properties of Comparative Example Series AHEFA content in HEFA/Jet A blend (vol %) 0.0 43.0 64.5 100.0 ComparativeExamples Jet A A-1 A-2 HEFA Test ASTM Method Property Aromatic Content(vol. %) D1319 or calculated 18.6 12 8 0.0 Density at 15° C. (g/cm³)D4052 0.7984 0.7839 0.7753 0.7570 Freezing Point (° C.) D5972 −43.2−45.9 −49.3 −57.5 Smoke Point (mm) D1322 24.3 30.65 36.35 >50.0*(automated) Hydrogen Content (mass %) D5291 14.01 14.45 14.73 15.60 NetHeat of Combustion or Gravimetric Energy Density D3338 or calculated43.3 43.6 43.8 44.1 (MJ/kg) Volumetric Energy Density Calculated 34,60034,200 33,900 33,400 (MJ/m³) *Actual values were beyond the indicateddetection limit

TABLE 11-3 Key Specification Properties of Comparative Example Series BGTL1 content in GTL1/Jet A blend (vol. %) 0.0 35.5 57.0 67.7 83.9 89.294.6 100.0 Comparative Examples ASTM Jet A B-1 B-2 B-3 B-4 B-5 B-6 GTL1Test Method Property Aromatic D1319 or 18.6 12.0 8.0 6.0 3.0 2.0 1.0 0.0Content (vol. %) calculated Density at 15° C. D4052 0.7984 0.7761 0.76360.7568 0.7467 0.7433 0.7396 0.7359 (g/cm³) Freezing Point D5972 −43.2−49.2 NA −58.1 NA NA −55.8 −54.6 (° C.) Smoke Point D1322 24.3 32.539.05 43.7 >50.0* >50.0* >50.0* >50.0* (mm) (automated) Hydrogen D529114.01 14.55 14.84 15.06 15.31 15.40 15.52 15.60 Content (wt. %) Net Heatof D3338 or 43.3 43.6 43.8 43.9 44.1 44.1 44.2 44.2 Combustion orcalculated Gravimetric Energy Density (MJ/kg) Volumetric Calculated34,600 33,900 33,400 33,200 32,900 32,800 32,700 32,600 Energy Density(MJ/m³) *Actual values were beyond the indicated detection limit

TABLE 11-4 Key Specification Properties of Comparative Example Series CGTL2 content in GTL2/Jet A blend (vol. %) 0.0 35.5 57.0 67.7 83.9 89.294.6 100.0 Comparative Examples ASTM Jet A C-1 C-2 C-3 C-4 C-5 C-6 GTL2Test Method Property Aromatic D1319 or 18.6 12.0 8.0 6.0 3.0 2.0 1.0 0.0Content (vol. %) calculated Density at 15° C. D4052 0.7984 0.7823 0.77310.7682 0.7609 0.7586 0.7560 0.7538 (g/cm³) Freezing Point D5972 −43.2−47.2 NA −50.1 NA NA −49.5 −49.3 (° C.) Smoke Point D1322 24.3 31.4 37.642.3 49.9 >50.0* >50.0* >50.0* (mm) (automated) Hydrogen D5291 14.0114.47 14.78 14.93 15.18 15.21 15.32 15.42 Content (mass %) Net Heat ofD3338 or 43.3 43.6 43.8 43.9 44.0 44.0 44.1 44.1 Combustion orcalculated Gravimetric Energy Density (MJ/kg) Volumetric Calculated34,600 34,100 33,800 33,700 33,500 33,400 33,300 33,300 Energy Density(MJ/m³) *Actual values were beyond the indicated detection limit

As can be seen from Table 11-1, SK1 can be blended to Jet A to meet JetA-1 specification as shown in Example 3-1 and can be blended to meetAN-8 specification as shown in Example 3-3, particularly without loss,but increase in volumetric energy density.

FIG. 1 compares the volumetric energy density (MJ/m³) of the jet fuelblends Example Series 3, Comparative Example Series A, ComparativeExample Series B, and Comparative Example Series C based on paraffinickerosene content in Jet A (vol. %). Also included for completeness arethe volumetric energy densities of the neat blend components ComparativeExample SK1, Comparative Example HEFA, Comparative Example GTL1,Comparative Example GTL2, and Comparative Example Jet A. The data show alinear blending relationship for all blends. The slopes of all theComparative Example Series data are negative, indicating increasedparaffinic kerosene content (whether via HEFA, GTL1, or GTL2) typicallyresults in an undesirable decrease in volumetric energy density.However, the slope of the Example 3 data is positive, indicating thatincreased SK1 cyclo-paraffinic kerosene content resulted in increasedvolumetric energy density. This demonstrates the unique ability to blenda cyclo-paraffinic kerosene product such as SK1 into a kerosene basefuel without decreasing, but rather increase volumetric energy density.This is desirable because higher volumetric energy density results inaircraft flying greater distances using the same volume of fuel, or inother words, with greater payload range.

FIG. 2 compares the aromatics content (vol. %) versus volumetric energydensity (MJ/m³) of the jet fuel blends Example Series 3, ComparativeExample Series A, Comparative Example Series B, and Comparative ExampleSeries C. Also included for completeness are the aromatics contents ofthe neat blend components Comparative Example SK1, Comparative ExampleHEFA, Comparative Example GTL1, Comparative Example GTL2, andComparative Example Jet A. The data show a linear blending relationshipfor all blends. The slopes of all the Comparative Example Series dataare positive, indicating that increased volumetric energy densitytypically requires an undesirable increase in aromatics content.However, the slope of the Example Series 3 data is negative, indicatingincreased volumetric energy density with decreasing aromatics content.This demonstrates the unique ability to blend a cyclo-paraffinickerosene product such as SK1 into a kerosene base fuel to decreasearomatics content without decreasing, but rather increase volumetricenergy density. This is desirable because lower aromatics contentimproves engine operability and lifetime and reduces soot emissions; andhigher volumetric energy density results in aircraft flying greaterdistances using the same volume of fuel, or in other words, with greaterpayload range.

FIG. 3 compares the smoke point increase (mm) of jet fuel withvolumetric energy density (MJ/m³) of the jet fuel blends Example 3,Comparative Example Series A, Comparative Example Series B, andComparative Example Series C. Also included for completeness are thesmoke points of the neat blend components Comparative Example SK1,Comparative Example HEFA, Comparative Example GTL1, Comparative ExampleGTL2, and Comparative Example Jet A. The data show a non-linear blendingrelationship for all blends. The slopes of all the Comparative ExampleSeries data are negative, indicating increased volumetric energy densitytypically requires an undesirable decrease in smoke point. However, theslope of the Example 3 data is positive, indicating increased volumetricenergy density with increasing smoke point. This demonstrates the uniqueability to blend a cyclo-paraffinic kerosene product such as SK1 into akerosene base fuel to increase volumetric energy density withoutdecreasing, but rather increase smoke point. This is desirable becausehigher smoke point indicates a cleaner-burning fuel; and highervolumetric energy density results in aircraft flying greater distancesusing the same volume of fuel, or in other words, with greater payloadrange.

FIG. 4 compares the freezing point increase (° C.) of jet fuel withvolumetric energy density (MJ/m³) of the jet fuel blends Example Series3, Comparative Example Series A, Comparative Example Series B, andComparative Example Series C. Also included for completeness are thefreezing points of the neat blend components Comparative Example SK1,Comparative Example HEFA, Comparative Example GTL1, Comparative ExampleGTL2, and Comparative Example Jet A. The data show a non-linear blendingrelationship for all blends. The Comparative Example Series dataindicate increased volumetric energy density typically requires anundesirable increase in freezing point. However, the Example 3 data showincreased volumetric energy density with decreasing freezing point. Thisdemonstrates the unique ability to blend a cyclo-paraffinic keroseneproduct such as SK1 into a kerosene base fuel to increase volumetricenergy density without increasing, but rather decrease the freezingpoint. This is desirable because a lower freezing point enables a fuelto meet more stringent specifications (such as for AN-8) or to fly moredirect routes through colder areas, and have wider applicability forcold environments; and higher volumetric energy density results inaircraft flying greater distances using the same volume of fuel, or inother words, with greater payload range.

Example 4—Production of Modified Synthesized Cyclo-Paraffinic Kerosenefor Rocket Fuel Applications

A fraction of cyclo-paraffinic kerosene can be produced in a similarmanner to Example 1. The last distillation step can be modified to meeta flash point of greater than 60° C. and a final boiling point less than274° C. Estimated properties of the product from this modifiedfractionation are summarized in Table 12.

TABLE 12 Physical Properties of SK Produced with Modified FractionationDistillation Initial BP (C) 180 Temp @ 10% Rec. (C) 189 Temp @ 20% Rec.(C) 197 Temp @ 50% Rec. (C) 215 Temp @ 90% Rec. (C) 251 Final BP (C) 270Flash Point (C) 60 Density, 15 C (kg/m³) 828

Example 5—Rocket Fuel Blends

Liquid kerosene rocket fuel blends can be produced usingcyclo-paraffinic kerosene (SK) from Example 1 and Example 4 andcommercially available kerosene range hydrocarbon component ShellSol™D60, D70, D90S and D100S as indicated below. These liquid rocket fuelblends, their indicated blend ratios and their properties are summarizedin Table 13. Remainder of vol. % is the respective ShellSol components.

TABLE 13 Key Specification Properties of Example Series 5 Using Example1 SK content from Example 1 in respective ShellSol blend (vol. %) 62 3772 ShellSol ™ Series ASTM D70 D60 D100S Test Method Property InitialBoiling Point Distillation 175 180 180 (° C.) Final Boiling PointDistillation 265 234 274 (° C.) Flash Point (° C.) D56 >60 >60 >60Density at 15° C. D4052 805 803 808 (kg/m³) Freezing Point (° C.) D5972<-51 <-51 <-51 Viscosity@−34° C. ) D445 est. 9.5  est. 8.5  est. 11  (cSt) Hydrogen Content D5291 est. 14.3 est. 14.3 est. 14.3 (mass %) NetHeat of D3338 or est. 43.9 est. 44.4 est. 43.8 Combustion or calculatedGravimetric Energy Density (MJ/kg) Key Specification Properties ofExample Series 5 Using Example 4 SK content from Example 4 in respectiveShellSol blend (vol. %) 79 74 62 37 ShellSol ™ Series ASTM D100S D90SD70 D60 Test Method Property Flash Point (° C.) D56 ≥60 ≥60 ≥60 ≥60Density at 15° C. D4052 821 819 815 809 (kg/m³) Freezing Point (° C.)D5972 <−51 <−51 <−51 <−51 Viscosity@−34° C. D445 est. 14 est. 13 est.12.3 est. 10.5 (cSt) Hydrogen Content D5291 ≥13.8 ≥13.8 ≥13.8 ≥13.8(mass %) Net Heat of D3338 or ≥43.03 ≥43.03 ≥43.03 ≥43.03 Combustion orcalculated Gravimetric Energy Density (MJ/kg)

It is expected that the above blends will meet the RP rocket fuelspecifications.

We claim:
 1. A method of increasing volumetric energy content of akerosene based-propulsion fuel comprising: a. providing a quantity ofkerosene base fuel having a boiling point in the range of 130° C. to300° C., at atmospheric pressure, flash point of 38° C. or abovemeasured by ASTM D56, and a density at 15° C. of at least 760 kg/m³; b.providing a quantity of synthetic cyclo-paraffinic kerosene fuelblending component comprising at least 99.5 mass % of carbon andhydrogen content and at least 50 mass % of cyclo-paraffin, saidcyclo-paraffinic kerosene fuel blending component having a boiling pointof at most 300° C. at atmospheric pressure, flash point of 38° C. orabove, a density at 15° C. of at least 800 kg/m³ and freezing point of−60° C. or lower; and c. blending a quantity of the syntheticcyclo-paraffinic kerosene fuel blending component and the kerosene basefuel in amount effective to increase the volumetric energy contentproviding a blended fuel.
 2. The method of claim 1 wherein the kerosenebase fuel has a freeze point of −30° C. or below, preferably −40° C. orlower.
 3. The method of claim 1 wherein the kerosene base fuel has atotal aromatic content in the range of 3 vol. % to 25 vol. % measured byASTM D1319.
 4. The method of claim 3 wherein the increase in aromaticcontent of the blended fuel is minimal.
 5. The method of claim 1 whereinthe kerosene base fuel is a kerosene fuel meeting at least one of Jet A,Jet A-1, Jet B, F-24, JP-5, JP-7, JP-8, or AN-8 specification.
 6. Themethod of claim 1 wherein the smoke point of the blended fuel isincreased compared with the petroleum-derived kerosene.
 7. The method ofclaim 1 wherein the synthetic cyclo-paraffinic kerosene fuel blendingcomponent has a maximum iso- and n-paraffin content of less than 50 mass%
 8. The method of claim 1 wherein the synthetic cyclo-paraffinickerosene fuel blending component has at least 60 mass %. (ASTM D2425).9. The method of claim 1 wherein the synthetic cyclo-paraffinic kerosenefuel blending component has an aromatic content of at most 1.5 mass %(ASTM D2425).
 10. The method of claim 1 wherein the kerosene base fuelis upgraded to meet Jet A-1 specification or JP-8 specification; whereinthe kerosene base fuel have a freezing point of above −47° C., and thesynthetic cyclo-paraffinic kerosene fuel is blended in an amounteffective to lower the freezing point of the blended fuel to −47° C. orlower.
 11. The method of claim 1 wherein the kerosene base fuel isupgraded to meet AN-8 specification; wherein the kerosene base fuel havea freezing point of above −58° C., and the synthetic cyclo-paraffinickerosene fuel is blended in an amount effective to lower the freezingpoint of the blended fuel to −58° C. or lower.
 12. The method of claim 1wherein the kerosene base fuel is upgraded to meet Jet A or F-24specification; wherein the kerosene base fuel have a freezing point ofabove −40° C., and the synthetic cyclo-paraffinic kerosene fuel isblended in an amount effective to lower the freezing point of theblended fuel to −40° C. or lower.
 13. The method of claim 1 whereincomponent b is added in an amount of 1 to 97 vol %, provided that theamount is sufficient to increase the volumetric energy content.
 14. Themethod of claim 1 wherein the increase of the aromatic content is lessthan 2 vol. %.
 15. The method of claim 1 wherein the syntheticcyclo-paraffinic kerosene fuel blending component have a freezing pointof −65° C. or below.
 16. The method of claim 1 wherein the syntheticcyclo-paraffinic kerosene fuel blending component have a density of atmost 845 kg/m³.
 17. The method of claim 16 wherein the syntheticcyclo-paraffinic kerosene fuel blending component has a density of atleast 810 kg/m³.
 18. The method of claim 1 wherein further comprising d)blending an additional propulsion fuel blending component to the blendedfuel.
 19. The method of claim 18 wherein the additional propulsion fuelblending component is a kerosene or naphtha.
 20. A method of operating ajet engine comprising burning in said jet engine a jet fuel prepared bythe method according to claim
 1. 21. A method of operating a jet enginecomprising burning in said jet engine a jet fuel prepared by the methodaccording to claim
 5. 22. A method of operating a jet engine comprisingburning in said jet engine a jet fuel prepared by the method accordingto claim
 7. 23. A method of operating a jet engine comprising burning insaid jet engine a jet fuel prepared by the method according to claim 8.24. A method of operating a jet engine comprising burning in said jetengine a jet fuel prepared by the method according to claim
 10. 25. Amethod of operating a jet engine comprising burning in said jet engine ajet fuel prepared by the method according to claim
 11. 26. A method ofoperating a jet engine comprising burning in said jet engine a jet fuelprepared by the method according to claim 12.